A commonly used vehicle for moving earth is a bulldozer. A bulldozer is usually fitted with a blade which is attached to the bulldozer by a pair of arms. Each of the arms is pivotally attached to the bulldozer at one end, and the blade may be raised or lowered relative to the bulldozer.
A known device for digging-out rocks is a ripper which attaches to the rear of a vehicle, such as a bulldozer. In order to remove a boulder, the bulldozer straddles the buried boulder, allowing the tooth of the ripper to engage the boulder as the bulldozer passes over it.
Devices are also known which extend outwardly from the blade of a bulldozer for shaping a slope.
U.S. Pat. No. 3,429,381 shows a slope blade (for a bulldozer) which comprises a blade pivotally mounted to a hinge, which is pivotally mounted for rotation about a vertical axis. A hydraulic cylinder extends from the hinge to the blade to pivot the blade about a horizontal axis, and an adjustable arm extends from another arm (attached to the bulldozer) to the blade for adjustment of the blade about a vertical axis.
U.S. Pat. No. 3,430,706l shows an attachment which is pivotally mounted to a bulldozer blade. The attachment rotates about a vertical axis in response to the extension of a hydraulic cylinder.
U.S. Pat. No. 3,464,499 shows a blade for shaping a slope. The blade is attached to a bulldozer arm and is rotatable about a horizontal axis which is generally parallel to the direction of the arm.
U.S. Pat. No. 4,079,791 shows an adjustable blade for attachment to a bulldozer. The blade is pivotally mounted for rotation about a horizontal axis in response to action of a hydraulic cylinder.